Within a distributed computing environment, there may be multiple communications networks among the nodes of the environment to provide high availability of the nodes. In order for messages initiated on one network to cross to another network, a router or a gateway between the networks is utilized.
It is usually the case that one of the networks provides significantly higher communication bandwidth than the others, and may be preferred for most communications. If the discrepancy between the bandwidths on the various networks is great enough, and for other reasons, applications may have to avoid automatic forwarding from one network to another. This is especially true for time and throughput sensitive applications, such as GPFS (General Parallel File System) offered by International Business Machines Corporation.
In those environments in which automatic forwarding is disabled, two distributed peers, X and Y, cannot communicate with each other, if a peer X is only able to communicate on one network and peer Y is only able to communicate on the other network. This is true even though there may be a third peer attached to both networks, which is reachable from both peers X and Y that could act as a gateway to reroute messages between X and Y.
One vexing aspect of this situation is that it is often difficult for peers X and Y to know that they cannot communicate with each other. If this happens, the applications on peers X and Y may continually try unsuccessfully to communicate between peers X and Y, or the applications may fall into an inconsistent state.
Thus, a need exists for a capability that provides the global status of communications networks of the environment, such that peers know with whom they can communicate. Further, a need exists for a capability that determines and/or provides a globally consistent desired group of reachable nodes of the environment.